Enhancing Stamping Efficiency: Sub-Zero and Wolf's Investment in Hydraulic Presses and QDC Equipment

In 2007, the pressroom at the Sub-Zero and Wolf manufacturing plant in Fitchburg, WI underwent significant expansion, nearly doubling its production capacity. This expansion included the addition of three Williams, White & Co. hydraulic presses (one 400-ton model and two 600-ton models), along with a 600-ton Minster mechanical press equipped with a coil-feed line. These press investments were made to support the introduction of new products and to bring previously outsourced stamping work in-house. Jeff Soule, fabrication supervisor for the manufacturing facility, emphasizes that these investments played a crucial role in strengthening the company's core competency in stamping and tool and die work.

All of the newly acquired presses were equipped with the same quick die change (QDC) equipment, which was originally specified for the firm's existing hydraulic presses (ranging from 300 to 900 tons). The QDC-system components, sourced from Hilma equipment by ROEMHELD North America, included hydraulically operated rollblocks, spring-return wedge clamps installed on the front side of each press, and hollow-cylinder-type T-slot clamps on the press backsides and upper slides. According to Hilma literature, the hollow-piston cylinder clamps are specifically designed to securely clamp dies on subplates with U-slots. These clamps feature single-acting spring return, and the cylinder's spherical washer adjusts to accommodate irregular clamping surfaces.

“Hydraulic die clamping provides the safe yet quick die changes we strive for,” says maintenance superintendent Mark Long. “We don’t have to worry whether or not the clamps are torqued appropriately, as we would with mechanically actuated clamps.

"We just have to program the required setpoints for the pressure on each clamp, and the press control monitors the hydraulic system to ensure we get the pressure we need. And, when we change dies, proximity sensors at each clamp location sense whether the clamps are in their home positions. The system prevents a die from being opened until every clamp is ready, so we don’t open the die with one clamp still activated.”